The disadvantages of previous air breathing apparatus include their weight, bulk, awkwardness, restrictions they create in closed confinement spaces, their risk of explosion and the marginal minutes of breathable air they provide in both emergency and continuous duty situations.
Previous designs have often put the air supply either high on the back of the user or to the side of the user, causing the user's centre of gravity to be shifted, thus creating strain on the user when wearing the apparatus and making continuous use of the apparatus difficult.
Further, in industry, emergency escape apparatus typically only provide 5 minutes to 15 minutes of breathable air. This gives the user a false sense of security since documented evidence shows that in many cases more time is required. For miners, accidents can require that the miner have one to two hours of breathable air to allow for safe evacuation. Construction workers building additions beside operating gas plants and refineries have found insufficient evacuation routes in the past and found a 5–15 minute emergency air supply was not enough.
Other problems with self-contained breathing apparatus include the fact that they do not compensate for the size of the user, it is a well known fact that a large person consumers more air per minute than a smaller person. Thus by providing the same emergency device to both individuals, the large person will have less time to safely escape the hazardous situation.
One of the main drawbacks to increasing air supply is the weight of tanks to carry the air. These tanks are generally large metal cylinders that are charged to approximately 3000 psi.
One solution to the weight problem is to create composite vessels with a metal liner and a composite structural component. These vessels still however have to be sufficiently strong to prevent failure, and thus the pressure in these vessels is limited.
Another problem with current air vessels, especially filament-epoxy wound containers, is that they have several deficiencies. These vessels do not have a good impact resistence capability, and are susceptible to rupturing if damaged. Further, rupturing of these vessels generally causes fragments to be propelled at high speeds, endangering those near the vessel.
Another problem with fibre-epoxy windings is that they do not withstand adverse environmental conditions very well. Exposure to caustic environments is possible, for example, in firefighting applications or in breathing devices designed for evacuation from chemical or industrial plants. These devices therefore need protection from the adverse environment.